Hi, Hope someone can help with this. I would like to be able to set up a alarm on a car. It would only go off if the car got in certain distance of some point, say 100 feet.
In other words if the car drove up to where I work my alarm would sound that the car is nearby.
I looked a bit for proximity alarms and really couldn't find much what I was looking for. Any websites, adivce you could provide would help. Thank you
You could do something with a timer on a transmitter / receiver set up but it would be awkward. Garage door opener stuff falls in to that reception range I suppose but it's RF, not very precise.
What about those dog fences? Can you bury a line?
If you just want to detect a vehicle driving up, that's easy. I guess I should have asked that first. Something like this maybe?
That's easy if you have an Ademco or DSC wireless system that annunciates "trouble" for a missing transmitter. You'd have to program a transmitter into your system, set up a relay correlation to either turn on a light or start a local buzzer when it's actually "present" in the system, and place the transmitter on the car you wanted to monitor. If it's within 200 feet of the receiver, the light/buzzer would turn "on". If it's out of range (or the battery's dead), the light/buzzer would be "off". The down side is that your system would also display "trouble" for the missing transmitter, but I think if you set it up on a different partition you could get around that.
Frank Olson
ROFL!!!
Not that easy. You've got the concept but it's not that fast, Frank. It depends on the window. My guess is the systems you mention are probably at least an hour, the car has come and gone by then :-)
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Yeah... You'd need something that transmitted continuously which would mean you'ld have to either hard wire the sucker to the vehicle's electrical system (can a 9 volt transmitter work on 14 volts?? I don't think so), or trip some sort of relay... easy enough to do if wire it to the ignition. Turning the engine off would energize the relay and open the contacts to the transmitter (it would transmit the open) instantly and accomplish two things... It would "log" back on to the security system and show an open zone. Starting the car would have the effect of "closing" the zone. The problem I see is that it sounds like the OP won't have that kind of access to the vehicle. A more clandestine approach is required. Like one of those card transmitters from HID. The reader for that guy's expensive though... and you'd need a head end unit to power it as well...
Excellent solution, Karl. I didn't realize they still sold mercury switches (what with the environmental concerns and all). I suppose any good movement detection switch would work (and automotive types would be weather-proof too). While I'm thinking about this we should also warn the OP that you can't guarantee the range on the transmitter will always be optimal. I'm not sure what to suggest about that as I've often found the position of the transmitter can affect the signal strength/range.
I have done this. I used a ITI transmitter (long life) and a Mercury switch attached to the input terminals. Dip the transmitter (once programmed in to your system) in that stuff they sell to coat your tool handles for protection. Then mount it on the "ledge" underneath the front t bumper or somewhere else. As a call pulls up and slows down/parks, the mercury will shift back and forth causing the transmitter to transmit. On the ITI stuff, you can put it in group 25 (older panels) and it should be "non-supervised". This will cause the alarm to chime anytime the car pulls up withing range.
KM
Ok thanks for some of the suggestions, I looked up ITI transmitters and didn't see what I was looking for, I will have to dig a bit deeper.
I really thought that there was some type of simple device out there that had a long life battery in it that I could just slap under the car. Then set up the reciever/dection sensor inside, and be done with it.
Radio Shack wireless doorbell and a mercury switch.
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